Cap at resistors of electrical test probe
A lossy dielectric device dissipates, absorbs, and/or dampens electric fields. The lossy dielectric device may be used with any transmission path, such as a transmission line or resistor in a probe head. The lossy dielectric device preferably includes a lossy dielectric material contained within a container. The container is positionable and securable substantially adjacent the transmission path to improve the curve of a frequency response. Preferably, the container is insulative, puncture resistant, and thin. In some preferred embodiments, a temporary or permanent connection mechanism is also included.
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The present application is a continuation of U.S. patent application Ser. No. 11/018,134, filed Dec. 17, 2004, now U.S. Pat. No. 7,295,020. U.S. patent application Ser. No. 11/018,134 is an application claiming the benefit under 35 USC Section 119(e) of U.S. Provisional Patent Application Ser. No. 60/531,077, filed Dec. 18, 2003. The present application is based on and claims priority from these applications, the disclosures of which are hereby expressly incorporated herein by reference.
BACKGROUND OF INVENTIONThe present invention is directed to a lossy dielectric cap that dissipates electric fields that may be used near current transmission or conduction paths in a probing head of an electrical test probe.
As current flows through wires and electrical components, it generates electromagnetic fields. Some of the energy radiates around the wires and electrical components. At certain frequencies, the fields can reflect and bounce back into the wires and electrical components. This process tends to create a varying response with respect to frequency that is undesirable. Ideal test probes have a perfect curve frequency response (shown as a flat line on a frequency response graph) in which voltage in is equal to (or proportional to) voltage out.
Much of the undesired variation in frequency response is due to the fact that some electromagnetic energy radiates into space from the probe tips. This energy can couple back onto the probe circuitry after the attenuating resistor, increasing or decreasing the signal level depending on the phase of the radiated path.
It has long been known that ferrite material (e.g. ferrite caps) can be used to dissipate, absorb, and/or dampen magnetic fields. In the exemplary probe head 30 of
Other material such as conductive foam (e.g. foam with slightly conductive properties) and conductive films have also been used for solving problems with electromagnetic fields. None of these products have provided satisfactory results.
BRIEF SUMMARY OF THE INVENTIONIt is desirable to have a material that would dissipate, absorb, or dampen electric fields so that such material could be placed and secured in positions where the electric field is stronger, and reduce undesired signals.
The present invention is directed to a lossy dielectric device for use with a transmission path, such as a transmission line or resistor in a probe head. The lossy dielectric device preferably includes a lossy dielectric material contained within a container. The container is positionable and securable substantially adjacent to said transmission path to improve the curve of a frequency response. Preferably, the container is insulative, puncture resistant, and thin. In some preferred embodiments, a temporary or permanent connection mechanism is also included.
The foregoing and other objectives, features, and advantages of the invention will be more readily understood upon consideration of the following detailed description of the invention, taken in conjunction with the accompanying drawings.
As shown in
The present invention contemplates the use of a lossy dielectric cap device 100 at or near the resistors 60 and/or transmission line 62 of a probing head 30. The lossy dielectric cap 100 is preferably made from materials having a finite conductivity in which the electromagnetic fields can propagate, but lose energy. The conductivity should not be so low that the material functions as an insulator through which the electromagnetic fields would propagate with no attenuation. The conductivity should not be so high that the material functions as a good conductor from which the electromagnetic fields would be reflected back. In one preferred embodiment the lossy dielectric cap device 100 approximates the composition of a human finger.
As shown in
For most of the exemplary embodiments discussed herein, the lossy dielectric cap 100 includes a container 102 and dielectric material 104 (e.g. a dipole). It should be noted, however, that alternative embodiments could include any material that has a finite conductivity such that the electromagnetic field energy is dissipated.
The container 102 may be made or constructed of materials including, but not limited to, plastic, rubber, polymeric material, biologically compatible elastically deformable material, that is preferably insulative, puncture resistant, and thin. The container 100 may be all or partially flexible, may be semi-rigid or contain a semi-rigid component, or may be all or partially rigid (if properly formed).
The dielectric material 102 may be made or constructed of materials including, but not limited to, a saline solution, a polysiloxane or a silicone gel, bio-osmotic gel (e.g. the combination of a bio-compatible organic polymer and a solution of bio-compatible salt disclosed in U.S. Pat. No. 5,067,965 to Ersek, which is incorporated herein by reference), or any lossy dielectric material. The dielectric material 102 would most likely be an organic material. One exemplary dielectric material 102 would be a mixture that includes the following ingredients: buffered, isotonic liquid solution of a borate buffer system and sodium chloride, sorbic acid, and edentate disodium.
It should be noted that the connection mechanism 106 for connecting the lossy dielectric cap 100 to a probe may be integral with the probe. Alternatively, connection mechanism 106 for connecting the lossy dielectric cap 100 may be temporarily or permanently attachable to and/or removable from the probe. As an example of an integral connection mechanism 106, the housing 48 of a probe may include an integral compartment that functions as a container 102. An adhesive may be used as a temporary connection mechanism 106 or as a permanent connection mechanism 106. For example, if a temporary, semi-permanent, or removable adhesive (e.g. 3M #486 adhesive) is used as the connection mechanism 106 then the lossy dielectric cap 100 may be placed/secured in position and, if desired, removed later. Such an adhesive would allow a user to remove, replace, and/or reposition the lossy dielectric cap 100. This characteristic would make the lossy dielectric cap 100 removably interconnectable. Preferably, the temporary connection mechanism would not leave a residue when it is removed. If a permanent adhesive (e.g. epoxy or acrylate adhesive) is used as the connection mechanism 106, then the lossy dielectric cap 100, once placed, could not be removed. Mechanical mechanisms may also be used either as a temporary connection mechanism 106 or as a permanent connection mechanism 106.
As shown in
As set forth above,
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It should be noted that the specific embodiments of the lossy dielectric caps shown in the various placements set forth above are meant to be exemplary. Alternative lossy dielectric caps could be positioned in each of the various positions.
It should be noted that the present invention was described in terms of and in relation to the shown exemplary test probe. It should be noted that the present invention is not limited to this test probe. Alternative probes could have a single test probe tip. Alternative probes could have alternative bandwidths. Alternative test probes might not incorporate an amplifier near the probe tips.
It should be noted that the lossy dielectric cap of the present invention may be used with transmission paths that are not in a test probe. For example, alternate transmission paths may be on a circuit board, a hybrid circuit, or in any electric device where radiated electromagnetic fields may be problematic.
The terms and expressions that have been employed in the foregoing specification are used as terms of description and not of limitation, and are not intended to exclude equivalents of the features shown and described or portions of them. The scope of the invention is defined and limited only by the claims that follow.
Claims
1. A lossy dielectric device for use with a transmission path, said device comprising:
- (a) a container;
- (b) lossy dielectric material contained within said container; and
- (c) said container positionable substantially adjacent said transmission path to improve the curve of a frequency response.
2. The lossy dielectric device of claim 1 wherein said container is insulative, puncture resistant, and thin.
3. The lossy dielectric device of claim 1 wherein said container is made of a material selected from the group consisting of:
- (a) plastic;
- (b) rubber;
- (c) polymeric material; and
- (d) biologically compatible elastically deformable material.
4. The lossy dielectric device of claim 1 wherein said container has a structure selected from the group consisting of:
- (a) an at least partially flexible structure;
- (b) a completely flexible structure; and
- (c) a structure with a semi-rigid bottom side and a flexible upper side.
5. The lossy dielectric device of claim 1 wherein said lossy dielectric material is selected from a group consisting of:
- (a) a mixture of salt and water;
- (b) saline solution;
- (c) a polysiloxane or a silicone gel; and
- (d) bio-osmotic gel.
6. The lossy dielectric device of claim 1 further comprising at least one connection mechanism selected from the group consisting of:
- (a) at least one permanent connection mechanism; and
- (b) at least one temporary connection mechanism.
7. The lossy dielectric device of claim 1 further comprising a layer of ferrite material.
8. The lossy dielectric device of claim 1, wherein said lossy dielectric material is a lossy dielectric fluid, a “squishy” material, or a formable material enclosed in said container.
9. A probing head comprising:
- (a) a transmission path;
- (b) a container;
- (c) lossy dielectric material contained within said container; and
- (d) said container securable substantially adjacent said transmission path to improve the curve of a frequency response.
10. The probing head of claim 9 wherein said container is insulative, puncture resistant, and thin.
11. The probing head of claim 9 wherein said container is made of a material selected from the group consisting of:
- (a) plastic;
- (b) rubber;
- (c) polymeric material; and
- (d) biologically compatible elastically deformable material.
12. The probing head of claim 9 wherein said container has a structure selected from the group consisting of:
- (a) an at least partially flexible structure;
- (b) a completely flexible structure; and
- (c) a structure with a semi-rigid bottom side and a flexible upper side.
13. The probing head of claim 9 wherein said lossy dielectric material is selected from a group consisting of:
- (a) a mixture of salt and water;
- (b) saline solution;
- (c) a polysiloxane or a silicone gel; and
- (d) bio-osmotic gel.
14. The probing head of claim 9 further comprising at least one connection mechanism selected from the group consisting of:
- (a) at least one permanent connection mechanism; and
- (b) at least one temporary connection mechanism.
15. The probing head of claim 9 further comprising a layer of ferrite material.
16. The probing head of claim 9, wherein said lossy dielectric material is a lossy dielectric fluid, a “squishy” material, or a formable material enclosed in said container.
17. A frequency response improving system, said system comprising:
- (a) a probing head;
- (b) a transmission path associated with said probing head;
- (c) a container;
- (d) lossy dielectric material contained within said container; and
- (e) said container positionable and securable substantially adjacent at least part of said transmission path to improve the curve of a frequency response.
18. The system of claim 17 wherein said container has a structure selected from the group consisting of:
- (a) an at least partially flexible structure;
- (b) a completely flexible structure; and
- (c) a structure with a semi-rigid bottom side and a flexible upper side.
19. The system of claim 17, wherein said lossy dielectric material is a lossy dielectric fluid, a “squishy” material, or a formable material enclosed in said container.
20. A frequency response improving system for use with a probing head having a transmission path, said system comprising:
- (a) a container;
- (b) lossy dielectric material contained within said container; and
- (c) said container positionable and securable substantially adjacent at least part of said transmission path to improve the curve of a frequency response.
21. The probing head of claim 20 wherein said container has a structure selected from the group consisting of:
- (a) an at least partially flexible structure;
- (b) a completely flexible structure; and
- (c) a structure with a semi-rigid bottom side and a flexible upper side.
22. The system of claim 20, wherein said lossy dielectric material is a lossy dielectric fluid, a “squishy” material, or a formable material enclosed in said container.
2488328 | November 1949 | Francis |
3256484 | June 1966 | Terry |
5045781 | September 3, 1991 | Gleason et al. |
5067965 | November 26, 1991 | Ersek et al. |
6275054 | August 14, 2001 | Boyle |
6538524 | March 25, 2003 | Miller |
6632534 | October 14, 2003 | Skaling et al. |
6664914 | December 16, 2003 | Longstaff et al. |
7012482 | March 14, 2006 | Rawnick et al. |
7295020 | November 13, 2007 | Campbell et al. |
- LeCroy WaveLink D600, D300, D200, High Bandwidth Probes Probing Solutions, 2003, 4 pages, http://www.lecoln.com.tw/getfile/lecroy/Datasheet/WaveLink/WaveLink—DS.pdf.
- LeCroy Announces WaveLink Probe Family for Test of PCI Express, Serial ATA and other High Bandwidth Applications, 2003, 4 pages, http://www.lecroy.com/ProductPress/FY03/021903.asp.
Type: Grant
Filed: Aug 3, 2007
Date of Patent: Apr 28, 2009
Patent Publication Number: 20070273360
Assignee: LeCroy Corporation (Chestnut Ridge, NY)
Inventors: Julie A. Campbell (Beaverton, OR), Lawrence W. Jacobs (Beaverton, OR)
Primary Examiner: Minh N Tang
Attorney: Law Office of Karen Dana Oster, LLC
Application Number: 11/890,095
International Classification: G01R 31/02 (20060101);